1. Field of the Invention
The present invention relates to a cylinder-piston arrangement, in particular, to a cylinder-piston arrangement for a reciprocating piston vacuum pump, and more specifically, to a sealing arrangement for a cylinder-piston arrangement of a reciprocating piston vacuum—pump for sealing a gap between a cylinder wall and a piston displaceable in the cylinder, which sealing arrangement includes at least one L-shaped annular seal having one of its legs secured on the piston for providing a static sealing, and its another free leg adjoining the cylinder wall for providing a dynamic sealing
2. Description of the Prior Art
Since several years, reciprocating piston vacuum pumps have successfully be used as so-called “dry forevacuum pumps.” They find application primarily there where forevacuum, which is free from working fluid, e.g., oil, must be produced because a return flow of working fluid into a recipient cannot be tolerated. Piston vacuum pumps include one or more cylinders in which a piston reciprocates, whereby the volume of the compression chamber is periodically increases and decreases. Within a time period during which the volume of the compression chamber decreases, the gas is compressed and is expelled at the end of the piston movement.
For a proper function of a dry piston vacuum pump, sealing of the gap between the piston and the inner wall is very important. A L-shaped seal such as described in German Publication DE-OS 103 37 298, proved itself as a seal for sealing the gap. With such a seal, one of the seal leg is secured in the piston whereas the other leg is slightly inclined toward the cylinder axis, contacting with its end the inner wall of the cylinder. The above-described L-shaped seal provides for a construction with a small dead space. A suitable material selection permits operation of the pump free of a working fluid.
During a lasting operation, an L-shaped seal is subjected to large loads which could lead to a high wear that is incompatible with high requirements to endurance characteristics of such a seal.
Accordingly, the object of the present invention is a seal arrangement for a cylinder-piston arrangement of a piston vacuum pump and that would have, at the same time, a reduced wear.